Duodenal acidification and secretin, but not intraduodenal fat, inhibit human gastric acid secretion via prostaglandins

The recurrent bleeding risk of a Forrest IIc lesion at the second-look endoscopy can be indicated by high Rockall scores ≥ 6

Background

The Forrest classification is widely applied to guide endoscopic hemostasis for peptic ulcer bleeding. Accordingly, practice guidelines suggest medical treatment only for ulcer with a Forrest IIc lesion because it has low rebleeding risk even without endoscopic therapy, ranging from 0 to 13%. However, the risk ranges widely and it is unclear who is at risk of rebleeding with such a lesion. This study assessed whether the Rockall score, which evaluates patients holistically, could indicate the risk of recurrent bleeding among patients with a Forrest IIc lesion at the second-look endoscopy.

Methods

Patients who had peptic ulcer bleeding with Ia-IIb lesions received endoscopic hemostasis at the primary endoscopy, and they were enrolled if their Ia-IIb lesions had been fading to IIc at the second-look endoscopy after 48- to 72-h intravenous proton pump inhibitor (PPI) infusion. Primary outcomes were rebleeding during the 4th–14th day and 4^th–28th day after the first bleeding episode.

Results

The prospective cohort study enrolled 140 patients, who were divided into a Rockall scores ≥ 6 group or a Rockall scores < 6 group. The rebleeding rates in the Rockall scores ≥ 6 group and the Rockall scores < 6 group during the 4th–14th day and the 4th–28th day were 13/70 (18.6%) versus 2/70 (2.9%), p = 0.003 and 17/70 (24.3%) versus 3/70 (4.3%), p = 0.001, respectively, based on an intention-to-treat analysis and 5/62 (8.1%) versus 0/68 (0%), p = 0.023 and 6/59 (10.2%) versus 0/67 (0%), p = 0.009, respectively, based on a per-protocol analysis. The Kaplan–Meier curves showed that the Rockall scores ≥ 6 group had a significantly lower cumulative rebleeding-free proportion than the Rockall scores < 6 group (p = 0.01).

Conclusions

Combined Rockall scores ≥ 6 on arrival with a Forrest IIc lesion at the second-look endoscopy can identify patients at risk of recurrent peptic ulcer bleeding following initial endoscopic and intravenous PPI treatment.

Trial registration Trial registration identifier: NCT01591083

Multiple actions of secretin in the human body

The discovery of secretin initiated the field of endocrinology. Over the past century, multiple gastrointestinal functions of secretin have been extensively studied, and it was discovered that the principal function of this peptide in the gastrointestinal system is to facilitate digestion and to provide protection. In view of the late identification of secretin and the secretin receptor in various tissues, including the central nervous system, the pleiotropic functions of secretin have more recently been an area of intense focus. Secretin is a classical hormone, and recent studies clearly showed secretin's involvement in neural and neuroendocrine pathways, although the neuroactivity and neural regulation of its release are yet to be elucidated. This chapter reviews our current understanding of the pleiotropic actions of secretin with a special focus on the hormonal and neural interdependent pathways that mediate these actions.

Biochemical aspects in autism spectrum disorders: updating the opioid-excess theory and presenting new opportunities for biomedical intervention

Autism is a lifelong condition usually described as affecting social, cognitive and imaginative abilities. For many years, parents and some professionals have observed that in concordance with the behavioural and psychological symptoms of the condition, there are a number of physiological and biochemical correlates which may also be of relevance to the syndrome. One area of interest that encompasses many of these observations is the opioid-excess theory of autism. The main premise of this theory is that autism is the result of a metabolic disorder. Peptides with opioid activity derived from dietary sources, in particular foods that contain gluten and casein, pass through an abnormally permeable intestinal membrane and enter the central nervous system (CNS) to exert an effect on neurotransmission, as well as producing other physiologically-based symptoms. Numerous parents and professionals worldwide have found that removal of these exogenously derived compounds through exclusion diets can produce some amelioration in autistic and related behaviours. There is a surprisingly long history of research accompanying these ideas. The aim of this paper is to review the accompanying evidence in support of this theory and present new directions of intervention as a result of it.

Nonsteroidal anti-inflammatory drug gastropathy at the new millennium: mechanisms and prevention

OBJECTIVES

Nonsteroidal anti-inflammatory drug (NSAID)-induced gastrointestinal (GI) toxicity remains the most frequent adverse drug event in the United States. The objective of this review is to update clinicians in recent advances in basic and clinical investigation regarding the pathogenesis and management of NSAID gastropathy.

METHODS

Based upon an extensive review of the published literature and abstracts of key work within the past decade, the framework for new approaches to the prevention and treatment of NSAID-associated ulceration is summarized.

RESULTS

The pathophysiology of NSAID-induced injury to the GI tract is multifaceted and includes both prostaglandin-dependent and independent components. The pharmaceutical industry has capitalized on the identification of two different isoforms of cyclooxygenase, enabling the development of specific inhibitors of one isoform that minimizes prostaglandin-dependent mechanisms that contribute to NSAID-induced injury. Clinical trials support the efficacy and reduced toxicity of these agents. Because acid exacerbates the injury initiated by NSAIDs, potent acid suppressive therapy, typically with proton pump inhibitors, is another common approach to the treatment of NSAID-related dyspepsia as well as NSAID-induced ulcer disease.

CONCLUSIONS

Recent improvements in the understanding of NSAID-induced damage and new drug development have provided the opportunity for effective anti-inflammatory therapy with reduced GI toxicity. This illustrates the importance of identifying patients at risk for potential complications and the appropriate use of strategies to prevent and treat NSAID-induced complications.

Adaptation of the exocrine pancreas to dietary fats

This article reviews studies on the adaptation of the exocrine pancreas to dietary fat. We include all the latest information about the mechanisms that underlie the adaptation of the secretory mechanism of the exocrine pancreas to the amount and the type of dietary fat. We review the kinetics of pancreatic adaptation and the mediators of the adaptive response of the pancreas including cellular and molecular mechanisms (modulation of intracellular messengers and gene expression of the different enzymes and secretagogues involved in the adaptation process). At the same time we include our results in this field in dogs and humans.

Eicosanoids and the stomach

Eicosanoids are arachidonic acid derivatives that include prostaglandins, thromboxanes, and leukotrienes. During the last three decades, it has become evident that these bioactive lipids play a pivotal role in gastric physiology. The goal of the present review is to describe their involvement in the normal regulation of gastric secretion and gastric motility, as well as in gastric mucosal defense. Their role in gastric mucosal mitogenesis, apoptosis, inflammation, and immune modulatory responses is also discussed.

Secretin inhibits gastric acid secretion via a vagal afferent pathway in rats

Secretin is an enterogastrone that inhibits gastric acid secretion and motility. Recently, it was reported that secretin inhibited gastric emptying via a capsaicin (Cap)-sensitive vagal afferent pathway. However, a possible role of the sensory afferent pathway in secretin-inhibited acid secretion has not been clarified. We investigated whether or not the acid secretion suppressed by secretin is modulated by a vagal and/or splanchnic afferent pathway in rats. Subdiaphragmatic perivagal (PV) or periceliac ganglionic (PCG) application of Cap (10 mg/ml) or vehicle was performed in both conscious and anesthetized rats 2 wk before experiments. Bilateral vagotomy was performed in some conscious rats 5 days before studies. Pentagastrin was administered intravenously at 0.6 microg . kg-1 . h-1. Secretin (20 pmol . kg-1 . h-1 iv) or 0.03 N HCl (4.32 ml/h id) was infused in conscious rats with gastric cannulas or anesthetized rats with ligation of the pylorus, respectively. A rabbit antisecretin serum was injected in some anesthetized rats before duodenal acidification. Secretin significantly inhibited pentagastrin-stimulated acid secretion by 63% (P < 0.01), which was abolished by both vagotomy and PV treatment of Cap in conscious rats. In anesthetized rats, duodenal infusion of 0.03 N HCl suppressed pentagastrin-induced acid secretion by 59.4% (P < 0.01), which was reversed not only by antisecretin serum but also by PV application of Cap. However, PCG treatment with Cap did not influence the inhibition by secretin or duodenal acidification in either awake or anesthetized rats. These results indicate that the inhibition by secretin of pentagastrin-stimulated acid secretion is mediated by a Cap-sensitive vagal afferent pathway but not via a splanchnic afferent pathway in rats.

NSAIDs, gastrointestinal injury, and cytoprotection

Gastrointestinal toxicity caused by nonsteroidal anti-inflammatory drugs (NSAIDs) is the most frequent drug side effect in the United States. NSAIDs are implicated in the development of complicated peptic ulcer disease and injury to the small bowel and colon. NSAIDs interfere with prostaglandin-mediated epithelial defense mechanisms and also cause direct epithelial toxicity. Current and future approaches to the prevention and management of NSAID injury are reviewed.